Method and apparatus for monitoring the tension of an advancing yarn

Abstract

The yarn tension at each of a plurality of yarn processing stations is continuously monitored, while continuously determining the mean value of the monitored tension at each station, and while also continuously determining the differential between the monitored value and the mean value. Also, an alarm signal is generated whenever the mean value leaves a predetermined tolerance range, and whenever the differential value leaves a second predetermined tolerance range. An alarm signal may serve to actuate a visual error indicator, or to shut down the associated processing station.

That which is claimed is: 
     
       1. A method of monitoring a variable parameter at a work station comprising the steps of continuously monitoring the value of the parameter, while continuously determining the mean value of the monitored parameter, and while also continuously determining the differential between the monitored value and the mean value, and   generating an alarm signal whenever the mean value leaves a predetermined tolerance range, or whenever the differential value leaves a second predetermined tolerance range.   
     
     
       2. A method of monitoring the tension of an advancing yarn at each of a plurality of monitored yarn processing stations of a yarn processing machine and comprising the steps of continuously monitoring the value of the tension of the advancing yarn at each of the yarn processing stations, while continuously determining the mean value of the monitored tension of each of the yarns, and while also continuously determining the differential between the monitored value and the mean value for each of the yarns, and   generating an alarm signal whenever the mean value for one of the advancing yarns leaves a predetermined tolerance range, or whenever the differential value for one of the advancing yarns leaves a second predetermined tolerance range.   
     
     
       3. The method as defined in claim 2 wherein the step of generating an alarm signal includes generating an alarm signal which is correlated to the associated yarn processing station upon the occurrence of either of said contingencies. 
     
     
       4. The method as defined in claim 2 wherein the step of generating an alarm signal includes severing the yarn being processed at the associated yarn processing station upon the occurrence of either of said contingencies. 
     
     
       5. The method as defined in claim 4 wherein the step of severing the yarn includes passing the alarm signal through a time delay circuit having a predetermined time constant so as to prevent the severing of the yarn in the event of the presence of a short and irrelevant alarm signal. 
     
     
       6. The method as defined in claim 5 wherein the step of severing the yarn includes generating a general alarm signal which is associated with a group of yarn processing stations of the machine to indicate that the yarn production at at least one of the associated stations has been terminated. 
     
     
       7. An apparatus for monitoring the tension of an advancing yarn at each of a plurality of monitored yarn processing stations of a yarn processing machine comprising sensor means for continuously monitoring the value of the tension of the advancing yarn at each of the yarn processing stations and for producing a continuous output signal representative of the value of the tension of each yarn,   circuit means operatively connected to the sensor means for continuously determining the mean value of the monitored tension of each of the yarns, and for also continuously determining the differential between the monitored value and the mean value for each of the yarns, and   means for generating an alarm signal whenever the mean value for one of the advancing yarns leaves a predetermined tolerance range, or whenever the differential value for one of the advancing yarns leaves a second predetermined tolerance range.   
     
     
       8. The apparatus as defined in claim 7 wherein said means for generating an alarm signal acts to generate an alarm signal whenever said mean value leaves its associated tolerance range and said differential value simultaneously leaves its associated tolerance range. 
     
     
       9. The apparatus as defined in claim 8 further comprising means for severing the yarn being processed at each of said processing stations, and control means for actuating said severing means at one of said stations whenever the mean value of the associated yarn leaves a predetermined tolerance range and whenever the differential value of the associated yarn leaves a second predetermined tolerance range. 
     
     
       10. The apparatus as defined in claim 9 wherein said control means includes time delay circuit means having a predetermined time constant so as to prevent the severing of a yarn in the event of a short and irrelevant departure from one of said tolerance ranges. 
     
     
       11. The apparatus as defined in claim 10 wherein said control means further includes means for generating a general alarm signal which is associated with a group of yarn processing positions of the machine to indicate that the yarn production at at least one of the associated positions has been terminated.